Filtern
Dokumenttyp
Sprache
- Englisch (3)
Referierte Publikation
- nein (3) (entfernen)
Schlagworte
- Strain measurement (3) (entfernen)
In 1882, the East-West suburban train viaduct was built through Berlin as part of the public traffic solution in the late 19th Century. Today, the only left over iron arch bridge is a pair of two arches Crossing the Spree river in the middle of Berlin. Before dismantling the former parallel two original pairs of iron arches and rebuilding new arches for the high-speed railway line through Berlin in 1997, BAM was involved in an extensive test program of the heritage iron arch structure. Especially the estimation of accumulated damage in critical details and the verification of the old material properties at early stage was important information to the bridge owners. The testing program included two strain and displacement measurement campaigns, non-destructive testing, materials testing and microscale metallographic analysis of critical details. The measured strain cycles were significant lower in number and size than expected. Most of the cycles were compression stress cycles only. The work was planned in Cooperation with the Berlin consultancy Professor Hilbers that was responsible for the design and calculation of the reconstruction measures. Additionally, after calculation of the possible reuse of the old arches, we compared measured data from strain measurements with the results from calculation.
The measured data and the calculated data show a good qualitative correlation.
The construction process of the New Berlin Main Station, the former Lehrter Bahnhof, has been monitored from the beginning. In this station, the main European east-western railway connection crosses the northsouth railway lines. Four east-western bridges, built in the first construction phase, carry the platforms for international lines and suburban train tracks. The outer two bridges carry the supports of the relatively flat glass roof, too. Since the glass roof is very sensitive to vertical displacements, the authorities required a complex monitoring system. This case study describes long-term measurements with classical and enhanced innovative sensors to monitor vertical displacements of neighboring glass roof supports. Additionally, traditional strain gauges were embedded parallel to long-gauge length fiber-optic strain sensors in the near-surface concrete of the partial prestressed bridges to reliably survey possible changes.
The measurements on site go along with long-term laboratory tests on prestressed concrete beams. Researchers study load effects and long-term environmental influences on two large-scale model beams, inside and outside the laboratory.
The monitoring system has been working stable as an early warning system for any changes of the structural conditions since 2002. All data are available on line for both the project team and the owner.